This renewal application seeks support to continue studies on the mechanism of action of progesterone on the mammalian uterus, using rabbit uteroglobin as a marker protein. In preceding years, we have isolated the chromosomal gene for uteroglobin and have purified the rabbit progesterone receptor. We now wish to study the interaction of the progesterone receptor with the uteroglobin gene, and the DNA sequences involved in control of transcription and hormonal regulation of expression. Using pure progesterone receptor, we will carry out binding reactions with different restriction endonuclease fragments of 5' DNA flanking the uteroglobin gene. As a receptor-binding domain has been identified in the chicken ovalbumin gene, we will examine whether the rabbit receptor interacts with this domain. Gene transfer techniques will be used to study control regions for transcription and regulation. By DNA-mediated transfer into HeLa cells in culture, we will assess integration and transcription of the uteroglobin gene and of 5'-deletion mutants generated by exonuclease digestion. Hormonal regulation of expression will be investigated by transformation of cultured T47D cells with uteroglobin DNA and different deletion mutants. Finally, the uteroglobin gene will be transferred into mice by microinjection into the pronucleus of one-cell fertilized eggs. Hormonal regulation will be studied by treatment of adult female transgenic mice and assay of uteroglobin production. These studies will provide information about how progesterone regulates the expression of a specific uterine gene coding for a secreted protein that may have importance for problems of fertility and infertility.